Does my i.p. address change when i'm on different networks?

Does my I.P. address change when I'm on different networks? Like if I'm on my home wireless network and say... Starbucks' wireless network?

Yes. The IP Address belongs to the person providing internet access. Its different for every provider of internet access. You just use it temporarily to access the internet.

Here's the thing. Every computer needs an ID to identify itself on the internet. The IP address assigned to you is this ID. Typically, your IP address can change every time you start up your computer. In practice if you remain with the same provider, it may not change that frequently.

Almost always on wireless networks you will not be assigned a real internet address but a local one. There are ranges of network numbers reserved for local networks that are not routed on the internet. These ranges are 192.168.x.x, 172.16-31.x.x, and 10.x.x.x. There is actually one more local network used in Windows networking but I can't remember the network number off the top of my head. In general addresses are assigned serially so whatever local address you get when you log in will be the first available one at that particular time so yes your local address will generally be different very time.

The reason for the local IP address is because if every device connected to the internet had its own real IP address we would have run out long ago. Devices on local networks are assigned local addresses and access the internet through a router that uses Network Address Translation or NAT so that all the devices on that local network share a single or few real IP address. Your real address will also change when you are on different networks; when you are home you will use one of your ISP's real IP addresses, when you are at Starbucks you will be using one of Starbucks or their ISP's IP addresses.

After you log into a wireless network bring up a command window (assuming Windows) and type ipconfig to see what your machine thinks your IP address is. I'll bet it will be an address in 192.168.x.x, 172.16-32.x.x or 10.x.x.x. Now go to a website like http://whatsmyip.org... and you will see what your real IP address in on the Internet.

If you have a WAP plugged directly into a broadband modem you might actually be assigned a real address at home. If this is your setup I'd recommend you get a router to put between your modem and WAP even if you don't need extra ports. You see in addition to allowing more devices NAT provides another security layer for your device since it makes it less reachable from the internet.